GPU Operator with Kata Containers

About the Operator with Kata Containers
- About NVIDIA Kata Manager
- NVIDIA Kata Manager Configuration
Benefits of Using Kata Containers
Limitations and Restrictions
Cluster Topology Considerations
Prerequisites
Overview of Installation and Configuration
Install the Confidential Containers Operator
Install the NVIDIA GPU Operator
- Procedure
- Verification
Run a Sample Workload
- Troubleshooting Workloads
About the Pod Annotation

About the Operator with Kata Containers

Note

Technology Preview features are not supported in production environments and are not functionally complete. Technology Preview features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. These releases may not have any documentation, and testing is limited.

Kata Containers are similar, but subtly different from traditional containers such as a Docker container.

A traditional container packages software for user-space isolation from the host, but the container runs on the host and shares the operating system kernel with the host. Sharing the operating system kernel is a potential vulnerability.

A Kata container runs in a virtual machine on the host. The virtual machine has a separate operating system and operating system kernel. Hardware virtualization and a separate kernel provide improved workload isolation in comparison with traditional containers.

The NVIDIA GPU Operator works with the Kata container runtime. Kata uses a hypervisor, like QEMU, to provide a lightweight virtual machine with a single purpose–to run a Kubernetes pod.

The following diagram shows the software components that Kubernetes uses to run a Kata container.

flowchart LR a[Kubelet] --> b[CRI] --> c[Kata\nRuntime] --> d[Lightweight\nQEMU VM] --> e[Lightweight\nGuest OS] --> f[Pod] --> g[Container]

Software Components with Kata Container Runtime

NVIDIA supports Kata Containers by using the Confidential Containers Operator to install the Kata runtime and QEMU. Even though the Operator isn’t used for confidential computing in this configuration, the Operator simplifies the installation of the Kata runtime.

About NVIDIA Kata Manager

When you configure the GPU Operator for Kata Containers, the Operator deploys NVIDIA Kata Manager as an operand.

The manager downloads an NVIDIA optimized Linux kernel image and initial RAM disk that provides the lightweight operating system for the virtual machines that run in QEMU. These artifacts are downloaded from the NVIDIA container registry, nvcr.io, on each worker node.

The manager also configures each worker node with a runtime class, kata-qemu-nvidia-gpu, and configures containerd for the runtime class.

NVIDIA Kata Manager Configuration

The following part of the cluster policy shows the fields related to the manager:

kataManager:
  enabled: true
  config:
    artifactsDir: /opt/nvidia-gpu-operator/artifacts/runtimeclasses
    runtimeClasses:
    - artifacts:
        pullSecret: ""
        url: nvcr.io/nvidia/cloud-native/kata-gpu-artifacts:ubuntu22.04-525
      name: kata-qemu-nvidia-gpu
      nodeSelector: {}
    - artifacts:
        pullSecret: ""
        url: nvcr.io/nvidia/cloud-native/kata-gpu-artifacts:ubuntu22.04-535-snp
      name: kata-qemu-nvidia-gpu-snp
      nodeSelector: {}
  repository: nvcr.io/nvidia/cloud-native
  image: k8s-kata-manager
  version: v0.1.0
  imagePullPolicy: IfNotPresent
  imagePullSecrets: []
  env: []
  resources: {}

The kata-qemu-nvidia-gpu runtime class is used with Kata Containers.

The kata-qemu-nvidia-gpu-snp runtime class is used with Confidential Containers and is installed by default even though it is not used with this configuration.

Benefits of Using Kata Containers

The primary benefits of Kata Containers are as follows:

Running untrusted workloads in a container. The virtual machine provides a layer of defense against the untrusted code.
Limiting access to hardware devices such as NVIDIA GPUs. The virtual machine is provided access to specific devices. This approach ensures that the workload cannot access additional devices.
Transparent deployment of unmodified containers.

Limitations and Restrictions

GPUs are available to containers as a single GPU in passthrough mode only. Multi-GPU passthrough and vGPU are not supported.
Support is limited to initial installation and configuration only. Upgrade and configuration of existing clusters for Kata Containers is not supported.
Support for Kata Containers is limited to the implementation described on this page. The Operator does not support Red Hat OpenShift sandbox containers.
Uninstalling the GPU Operator or the NVIDIA Kata Manager does not remove the files that the manager downloads and installs in the /opt/nvidia-gpu-operator/artifacts/runtimeclasses/kata-qemu-nvidia-gpu/ directory on the worker nodes.
NVIDIA supports the Operator and Kata Containers with the containerd runtime only.

Cluster Topology Considerations

You can configure all the worker nodes in your cluster for Kata Containers or you configure some nodes for Kata Containers and the others for traditional containers. Consider the following example.

Node A is configured to run traditional containers.

Node B is configured to run Kata Containers.

Node A receives the following software components:

NVIDIA Driver Manager for Kubernetes – to install the data-center driver.
NVIDIA Container Toolkit – to ensure that containers can access GPUs.
NVIDIA Device Plugin for Kubernetes – to discover and advertise GPU resources to kubelet.
NVIDIA DCGM and DCGM Exporter – to monitor GPUs.
NVIDIA MIG Manager for Kubernetes – to manage MIG-capable GPUs.
Node Feature Discovery – to detect CPU, kernel, and host features and label worker nodes.
NVIDIA GPU Feature Discovery – to detect NVIDIA GPUs and label worker nodes.

Node B receives the following software components:

NVIDIA Kata Manager for Kubernetes – to manage the NVIDIA artifacts such as the NVIDIA optimized Linux kernel image and initial RAM disk.
NVIDIA Sandbox Device Plugin – to discover and advertise the passthrough GPUs to kubelet.
NVIDIA VFIO Manager – to load the vfio-pci device driver and bind it to all GPUs on the node.
Node Feature Discovery – to detect CPU security features, NVIDIA GPUs, and label worker nodes.

Prerequisites

Your hosts are configured to enable hardware virtualization and Access Control Services (ACS). With some AMD CPUs and BIOSes, ACS might be grouped under Advanced Error Reporting (AER). Enabling these features is typically performed by configuring the host BIOS.
Your hosts are configured to support IOMMU.

If the output from running ls /sys/kernel/iommu_groups includes 0, 1, and so on, then your host is configured for IOMMU.

If a host is not configured or you are unsure, add the intel_iommu=on Linux kernel command-line argument. For most Linux distributions, you add the argument to the /etc/default/grub file:
```
...
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on modprobe.blacklist=nouveau"
...
```
On Ubuntu systems, run sudo update-grub after making the change to configure the bootloader. On other systems, you might need to run sudo dracut after making the change. Refer to the documentation for your operating system. Reboot the host after configuring the bootloader.
You have a Kubernetes cluster and you have cluster administrator privileges.

Overview of Installation and Configuration

Installing and configuring your cluster to support the NVIDIA GPU Operator with Kata Containers is as follows:

Label the worker nodes that you want to use with Kata Containers.

This step ensures that you can continue to run traditional container workloads with GPU or vGPU workloads on some nodes in your cluster. Alternatively, you can set the default sandbox workload to vm-passthrough to run confidential containers on all worker nodes.
Install the Confidential Containers Operator.

This step installs the Operator and also the Kata Containers runtime that NVIDIA uses for Kata Containers.
Install the NVIDIA GPU Operator.

You install the Operator and specify options to deploy the operands that are required for Kata Containers.

After installation, you can run a sample workload.

Install the Confidential Containers Operator

Perform the following steps to install and verify the Confidential Containers Operator:

Label the nodes to run virtual machines in containers. Label only the nodes that you want to run with Kata Containers.
```
$ kubectl label node <node-name> nvidia.com/gpu.workload.config=vm-passthrough
```
Set the Operator version in an environment variable:
```
$ export VERSION=v0.7.0
```

Install the Operator:

$ kubectl apply -k "github.com/confidential-containers/operator/config/release?ref=${VERSION}"

Example Output

namespace/confidential-containers-system created
customresourcedefinition.apiextensions.k8s.io/ccruntimes.confidentialcontainers.org created
serviceaccount/cc-operator-controller-manager created
role.rbac.authorization.k8s.io/cc-operator-leader-election-role created
clusterrole.rbac.authorization.k8s.io/cc-operator-manager-role created
clusterrole.rbac.authorization.k8s.io/cc-operator-metrics-reader created
clusterrole.rbac.authorization.k8s.io/cc-operator-proxy-role created
rolebinding.rbac.authorization.k8s.io/cc-operator-leader-election-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/cc-operator-manager-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/cc-operator-proxy-rolebinding created
configmap/cc-operator-manager-config created
service/cc-operator-controller-manager-metrics-service created
deployment.apps/cc-operator-controller-manager create

Optional: View the pods and services in the confidential-containers-system namespace:

$ kubectl get pod,svc -n confidential-containers-system

Example Output

NAME                                                 READY   STATUS    RESTARTS   AGE
pod/cc-operator-controller-manager-c98c4ff74-ksb4q   2/2     Running   0          2m59s

NAME                                                     TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
service/cc-operator-controller-manager-metrics-service   ClusterIP   10.98.221.141   <none>        8443/TCP   2m59s

Install the sample Confidential Containers runtime by creating the manifests and then editing the node selector so that the runtime is installed only on the labelled nodes.

Create a local copy of the manifests in a file that is named ccruntime.yaml:

$ kubectl apply --dry-run=client -o yaml \
    -k "github.com/confidential-containers/operator/config/samples/ccruntime/default?ref=${VERSION}" > ccruntime.yaml

Edit the ccruntime.yaml file and set the node selector as follows:

apiVersion: confidentialcontainers.org/v1beta1
kind: CcRuntime
metadata:
  annotations:
...
spec:
  ccNodeSelector:
    matchLabels:
      nvidia.com/gpu.workload.config: "vm-passthrough"
...

Apply the modified manifests:

$ kubectl apply -f ccruntime.yaml

Example Output

ccruntime.confidentialcontainers.org/ccruntime-sample created

Wait a few minutes for the Operator to create the base runtime classes.

Optional: View the runtime classes:

$ kubectl get runtimeclass

Example Output

NAME            HANDLER         AGE
kata            kata            13m
kata-clh        kata-clh        13m
kata-clh-tdx    kata-clh-tdx    13m
kata-qemu       kata-qemu       13m
kata-qemu-sev   kata-qemu-sev   13m
kata-qemu-snp   kata-qemu-snp   13m
kata-qemu-tdx   kata-qemu-tdx   13m

Install the NVIDIA GPU Operator

Procedure

Perform the following steps to install the Operator for use with Kata Containers:

Add and update the NVIDIA Helm repository:

$ helm repo add nvidia https://helm.ngc.nvidia.com/nvidia \
   && helm repo update

Specify at least the following options when you install the Operator. If you want to run Kata Containers by default on all worker nodes, also specify --set sandboxWorkloads.defaultWorkload=vm-passthough.

$ helm install --wait --generate-name \
   -n gpu-operator --create-namespace \
   nvidia/gpu-operator \
   --set sandboxWorkloads.enabled=true \
   --set kataManager.enabled=true

Example Output

NAME: gpu-operator
LAST DEPLOYED: Tue Jul 25 19:19:07 2023
NAMESPACE: gpu-operator
STATUS: deployed
REVISION: 1
TEST SUITE: None

Verification

Verify that the Kata Manager and VFIO Manager operands are running:

$ kubectl get pods -n gpu-operator

Example Output

NAME                                                         READY   STATUS      RESTARTS   AGE
gpu-operator-57bf5d5769-nb98z                                1/1     Running     0          6m21s
gpu-operator-node-feature-discovery-master-b44f595bf-5sjxg   1/1     Running     0          6m21s
gpu-operator-node-feature-discovery-worker-lwhdr             1/1     Running     0          6m21s
nvidia-kata-manager-bw5mb                                    1/1     Running     0          3m36s
nvidia-sandbox-device-plugin-daemonset-cr4s6                 1/1     Running     0          2m37s
nvidia-sandbox-validator-9wjm4                               1/1     Running     0          2m37s
nvidia-vfio-manager-vg4wp                                    1/1     Running     0          3m36s

Verify that the kata-qemu-nvidia-gpu and kata-qemu-nvidia-gpu-snp runtime classes are available:

$ kubectl get runtimeclass

Example Output

NAME                       HANDLER                    AGE
kata                       kata                       37m
kata-clh                   kata-clh                   37m
kata-clh-tdx               kata-clh-tdx               37m
kata-qemu                  kata-qemu                  37m
kata-qemu-nvidia-gpu       kata-qemu-nvidia-gpu       96s
kata-qemu-nvidia-gpu-snp   kata-qemu-nvidia-gpu-snp   96s
kata-qemu-sev              kata-qemu-sev              37m
kata-qemu-snp              kata-qemu-snp              37m
kata-qemu-tdx              kata-qemu-tdx              37m
nvidia                     nvidia                     97s

Optional: If you have host access to the worker node, you can perform the following steps:

Confirm that the host uses the vfio-pci device driver for GPUs:

$ lspci -nnk -d 10de:

Example Output

65:00.0 3D controller [0302]: NVIDIA Corporation GA102GL [A10] [10de:2236] (rev a1)
        Subsystem: NVIDIA Corporation GA102GL [A10] [10de:1482]
        Kernel driver in use: vfio-pci
        Kernel modules: nvidiafb, nouveau

Confirm that NVIDIA Kata Manager installed the kata-qemu-nvidia-gpu runtime class files:

$ ls -1 /opt/nvidia-gpu-operator/artifacts/runtimeclasses/kata-qemu-nvidia-gpu/

Example Output

configuration-nvidia-gpu-qemu.toml
kata-ubuntu-jammy-nvidia-gpu.initrd
vmlinuz-5.xx.x-xxx-nvidia-gpu
...

Run a Sample Workload

A pod specification for a Kata container requires the following:

Specify a Kata runtime class.
Specify a passthrough GPU resource.

Determine the passthrough GPU resource names:

kubectl get nodes -l nvidia.com/gpu.present -o json | \
  jq '.items[0].status.allocatable |
    with_entries(select(.key | startswith("nvidia.com/"))) |
    with_entries(select(.value != "0"))'

Example Output

{
   "nvidia.com/GA102GL_A10": "1"
}

Create a file, such as cuda-vectoradd-kata.yaml, like the following example:

apiVersion: v1
kind: Pod
metadata:
  name: cuda-vectoradd-kata
  annotations:
    cdi.k8s.io/gpu: "nvidia.com/pgpu=0"
    io.katacontainers.config.hypervisor.default_memory: "16384"
spec:
  runtimeClassName: kata-qemu-nvidia-gpu
  restartPolicy: OnFailure
  containers:
  - name: cuda-vectoradd
    image: "nvcr.io/nvidia/k8s/cuda-sample:vectoradd-cuda11.7.1-ubuntu20.04"
    resources:
      limits:
        "nvidia.com/GA102GL_A10": 1

The io.katacontainers.config.hypervisor.default_memory annotation starts the VM with 16 GB of memory. Modify the value to accommodate your workload.

Create the pod:

$ kubectl apply -f cuda-vectoradd-kata.yaml

View the logs from pod:

$ kubectl logs -n default cuda-vectoradd-kata

Example Output

[Vector addition of 50000 elements]
Copy input data from the host memory to the CUDA device
CUDA kernel launch with 196 blocks of 256 threads
Copy output data from the CUDA device to the host memory
Test PASSED
Done

Delete the pod:

$ kubectl delete -f cuda-vectoradd-kata.yaml

Troubleshooting Workloads

If the sample workload does not run, confirm that you labelled nodes to run virtual machines in containers:

$ kubectl get nodes -l nvidia.com/gpu.workload.config=vm-passthrough

Example Output

NAME               STATUS   ROLES    AGE   VERSION
kata-worker-1      Ready    <none>   10d   v1.27.3
kata-worker-2      Ready    <none>   10d   v1.27.3
kata-worker-3      Ready    <none>   10d   v1.27.3

About the Pod Annotation

The cdi.k8s.io/gpu: "nvidia.com/pgpu=0" annotation is used when the pod sandbox is created. The annotation ensures that the virtual machine created by the Kata runtime is created with the correct PCIe topology so that GPU passthrough succeeds.

The annotation refers to a Container Device Interface (CDI) device, nvidia.com/pgpu=0. The pgpu indicates passthrough GPU and the 0 indicates the device index. The index is defined by the order that the GPUs are enumerated on the PCI bus. The index does not correlate to a CUDA index.

The NVIDIA Kata Manager creates a CDI specification on the GPU nodes. The file includes a device entry for each passthrough device.

In the following sample /var/run/cdi/nvidia.com-pgpu.yaml file shows one GPU that is bound to the VFIO PCI driver:

cdiVersion: 0.5.0
containerEdits: {}
devices:
- containerEdits:
    deviceNodes:
    - path: /dev/vfio/10
name: "0"
kind: nvidia.com/pgpu